Compound graduations

[cannonmakerken]

I have a 71 year old 13 inch South Bend lathe and the compound graduations are behind the compound and the graduations for turning tapers are kind of worn. And my eyes aren't that great at my age. Isn't there another way to find the degrees for turning tapers. Like maybe using a hand held protractor to find the taper. Thanks Ken G.

 

[benmychree]

Using a protractor would get you in the neighborhood, the graduations are far from exact either, dur to wear on the carriage ways and cross feed ways. an exact setting is possible only using a fixed precision gage, by cut and try.

 

[epanzella]

A DI and some trig could get you really accurate.

 

[Aukai]

I cheat, I am math challenged, I figure the amount of taper over how long. Then get the half number, space the cutter out from the work, and run the distance. It should go from the amount spaced to just touching the work at the end of the run. I hope that makes sense. My dad had degrees in mathematics, the gene skipped me

 

[Flynth]

I cheat, I am math challenged, I figure the amount of taper over how long. Then get the half number, space the cutter out from the work, and run the distance. It should go from the amount spaced to just touching the work at the end of the run. I hope that makes sense. My dad had degrees in mathematics, the gene skipped me

That's a good method. Why do it harder when you don't have to? It's like with threading on the lathe. I used to set up a dial indicator, calculate depth in terms of cross slide travel etc... All until I saw Joe Pie video about his method that says to position your compound at 0. Touch on the work with your cross slide. Back off with compound quite a bit, move the desired thread depth with your cross slide and set your cross slide zero there. Touch off on the work again with your compound.

Now, you thread and it's dead simple. You feed with the compound until it reaches zero and you're exactly at your thread depth (minus part and told deflection, slop etc). Bonus point is that you can always back off with the cross slide and come back to zero if you need to interrupt etc. No need for paper and pen, writing down dial positions carefully not to overshoot... Best method ever

 

[mmcmdl]

A simple sine bar works great for precision tapers . No need for blocks if you don't have them , adjustable parallels are easy to set .

 

[Flynth]

A simple sine bar works great for precision tapers . No need for blocks if you don't have them , adjustable parallels are easy to set .

Are we talking on the lathe? How does one use a sine bar to set a compound on a lathe?

I always did similar as mentioned above. I would put a dial indicator in the tool post. Chuck a precise cylinder (or put it in the tailstock if the chuck is being used). Mark a certain distance on the bar and adjust the compound until I get the right amount of travel for that length.

 

[mmcmdl]

Sine bar goes on the compound , an indicator is fixed wherever possible . Move your carriage back and forth till you get 0-0 on the bar . The angle is set .

 

[BGHansen]

Another way is using a tapered gauge block between your work and the compound. The photo below isn't quite apples to applies as in the photo I'm setting the edge of the tool bit to a 30 deg. angle relative to the faced surface of the chucked stock. You can use a similar setup with a 30 or 60 degree block to set the compound for threading. Mine is an 12-piece import set that goes from 1/4 deg. to 30 in various steps. They're around $40.

A protractor would be your cheapest and easiest fix as mentioned above. You'd set the angle to "whatever" and be one and done though not as accurately as gauge blocks.

Bruce

 

[RJSakowski]

Tom Lipton, OxTools, did a video some time ago using a sine bar to set up a compound for cutting tapers. A 2.5" sine bar rather than the more common 5" sine bar works great for that purpose.